U.S. patent number 10,030,101 [Application Number 15/523,918] was granted by the patent office on 2018-07-24 for branched polycarbonate production method.
This patent grant is currently assigned to IDEMITSU KOSAN CO., LTD.. The grantee listed for this patent is IDEMITSU KOSAN CO., LTD.. Invention is credited to Noriyuki Kunishi, Yukiko Nagao, Kenji Sasaki, Kazuhiro Sekiguchi, Masayuki Takahashi.
United States Patent |
10,030,101 |
Kunishi , et al. |
July 24, 2018 |
Branched polycarbonate production method
Abstract
Provided is a method of producing a branched polycarbonate,
including: a step (a) of subjecting an alkali aqueous solution of a
dihydric phenol, phosgene, and a branching agent to a phosgenation
reaction in the presence of an organic solvent to provide a
reaction liquid; a step (b) of adding the alkali aqueous solution
of the dihydric phenol and a polymerization catalyst to the
reaction liquid obtained from the step (a) to provide a reaction
liquid containing a polycarbonate oligomer; a step (c) of
separating the reaction liquid containing the polycarbonate
oligomer obtained in the step (b) into an organic solvent phase
containing the polycarbonate oligomer and an aqueous phase; and a
step (d) of causing the organic solvent phase containing the
polycarbonate oligomer separated in the step (c) and the alkali
aqueous solution of the dihydric phenol to react with each other to
provide a reaction liquid containing the branched polycarbonate, in
which a ratio (x/y) of an addition amount of the polymerization
catalyst to be added in the step (b), which is represented by x
mol/hr, to a chloroformate group amount of the polycarbonate
oligomer in the reaction liquid obtained from the step (b), which
is represented by y mol/hr, is 0.0035 or more.
Inventors: |
Kunishi; Noriyuki (Ichihara,
JP), Sekiguchi; Kazuhiro (Chiba, JP),
Nagao; Yukiko (Tokyo, JP), Takahashi; Masayuki
(Taipei, TW), Sasaki; Kenji (Ichihara,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
IDEMITSU KOSAN CO., LTD. |
Tokyo |
N/A |
JP |
|
|
Assignee: |
IDEMITSU KOSAN CO., LTD.
(Tokyo, JP)
|
Family
ID: |
55909214 |
Appl.
No.: |
15/523,918 |
Filed: |
November 6, 2015 |
PCT
Filed: |
November 06, 2015 |
PCT No.: |
PCT/JP2015/081309 |
371(c)(1),(2),(4) Date: |
May 02, 2017 |
PCT
Pub. No.: |
WO2016/072491 |
PCT
Pub. Date: |
May 12, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170313817 A1 |
Nov 2, 2017 |
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Foreign Application Priority Data
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|
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Nov 7, 2014 [JP] |
|
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2014-227409 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G
64/06 (20130101); C08G 64/24 (20130101) |
Current International
Class: |
C08G
64/06 (20060101); C08G 64/24 (20060101) |
Field of
Search: |
;528/169,196,198 |
Foreign Patent Documents
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S59-191717 |
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Oct 1984 |
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JP |
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H07-102055 |
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Apr 1995 |
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JP |
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H07-103235 |
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Nov 1995 |
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JP |
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2005-126478 |
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May 2005 |
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JP |
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2005-239876 |
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Sep 2005 |
|
JP |
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2015-229766 |
|
Dec 2015 |
|
JP |
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WO-2011/043484 |
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Apr 2011 |
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WO |
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Other References
International Search Report for International Patent Application
No. PCT/JP2015/081309 dated Feb. 9, 2016. cited by
applicant.
|
Primary Examiner: Boykin; Terressa
Attorney, Agent or Firm: Foley & Lardner LLP
Claims
The invention claimed is:
1. A method of producing a branched polycarbonate, comprising: a
step (a) of subjecting an alkali aqueous solution of a dihydric
phenol, phosgene, and a branching agent to a phosgenation reaction
in the presence of an organic solvent to provide a reaction liquid;
a step (b) of adding the alkali aqueous solution of the dihydric
phenol and a polymerization catalyst to the reaction liquid
obtained from the step (a) to provide a reaction liquid containing
a polycarbonate oligomer; a step (c) of separating the reaction
liquid containing the polycarbonate oligomer obtained in the step
(b) into an organic solvent phase containing the polycarbonate
oligomer and an aqueous phase; and a step (d) of causing the
organic solvent phase containing the polycarbonate oligomer
separated in the step (c) and the alkali aqueous solution of the
dihydric phenol to react with each other to provide a reaction
liquid containing the branched polycarbonate, wherein a ratio (x/y)
of an addition amount of the polymerization catalyst to be added in
the step (b), which is represented by x mol/hr, to a chloroformate
group amount of the polycarbonate oligomer in the reaction liquid
obtained from the step (b), which is represented by y mol/hr, is
0.0035 or more.
2. The method of producing a branched polycarbonate according to
claim 1, wherein the polycarbonate oligomer has a weight-average
molecular weight of 5,000 or less.
3. The method of producing a branched polycarbonate according to
claim 1, wherein the branching agent comprises a compound
represented by the following general formula (I): ##STR00005##
wherein R represents a hydrogen atom or an alkyl group having 1 to
5 carbon atoms, and R.sup.1 to R.sup.6 each represent a hydrogen
atom, an alkyl group having 1 to 5 carbon atoms, or a halogen
atom.
4. The method of producing a branched polycarbonate according to
claim 3, wherein the compound represented by the general formula
(I) comprises 1,1,1-tris(4-hydroxyphenyl)ethane.
5. The method of producing a branched polycarbonate according to
claim 1, wherein the dihydric phenol comprises a compound
represented by the following general formula (1): ##STR00006##
wherein R.sup.11 and R.sup.12 each independently represent a
halogen atom, an alkyl group having 1 to 6 carbon atoms, or an
alkoxy group having 1 to 6 carbon atoms, Z represents a single
bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene
group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to
15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon
atoms, a fluorenediyl group, an arylalkylene group having 7 to 15
carbon atoms, an arylalkylidene group having 7 to 15 carbon atoms,
--S--, --SO--, --SO.sub.2--, --O--, or --CO--, and a and b each
independently represent an integer of from 0 to 4.
6. The method of producing a branched polycarbonate according to
claim 5, wherein the compound represented by the general formula
(1) comprises 2,2-bis(4-hydroxyphenyl)propane.
7. The method of producing a branched polycarbonate according to
claim 1, further comprising adding a terminal stopper to the
reaction liquid obtained from the step (a).
8. The method of producing a branched polycarbonate according to
claim 1, further comprising a step (e) of separating the reaction
liquid containing the branched polycarbonate obtained in the step
(d) into an organic solvent phase containing the branched
polycarbonate and an aqueous phase containing an unreacted dihydric
phenol.
9. The method of producing a branched polycarbonate according to
claim 8, wherein at least part of the aqueous phase containing the
unreacted dihydric phenol separated in the step (e) is used as the
alkali aqueous solution of the dihydric phenol to be added in the
step (b).
10. The method of producing a branched polycarbonate according to
claim 1, wherein the chloroformate group amount of the
polycarbonate oligomer in the reaction liquid obtained from the
step (b) is defined as a molar amount per unit time of the organic
solvent phase containing the polycarbonate oligomer separated in
the step (c).
11. The method of producing a branched polycarbonate according to
claim 1, wherein the polymerization catalyst comprises
triethylamine.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a U.S. national stage entry of
International Patent Application No. PCT/JP2015/081309, filed Nov.
6, 2015, which claims the benefit of priority to Japanese Patent
Application No. 2014-227409, filed Nov. 7, 2014, the entireties of
which are hereby incorporated by reference.
TECHNICAL FIELD
The present invention relates to a method of producing a branched
polycarbonate, and more specifically, to a method of producing a
branched polycarbonate excellent in production efficiency, based on
an interfacial polymerization method.
BACKGROUND ART
Polycarbonates each have excellent characteristics, such as
transparency, heat resistance, and mechanical characteristics, and
hence have been used in a wide variety of applications including:
casings for OA equipment and a household electric appliance; parts
in electrical and electronic fields; and optical materials, such as
a lens. Many of the polycarbonates used in the wide variety of
applications are each a linear polymer obtained by causing a
dihydric phenol and a carbonate precursor, such as phosgene, to
react with each other. However, the polymer shows Newtonian flow
behavior under a melt processing condition, and hence when blow
molding, extrusion molding, or foam molding is performed, drawdown
is liable to occur owing to its self-weight. The drawdown causes a
problem particularly in the case of large-scale molding.
In order to alleviate such problem, a branched polycarbonate that
shows non-Newtonian flowability under a melt processing condition
and hence hardly causes drawdown at the time of its melting has
been preferably adopted in the above-mentioned molding
applications.
The production of the branched polycarbonate through the use of an
interfacial polymerization method or an ester exchange method has
been known as a method of producing the polycarbonate. When the
branched polycarbonate is produced by using the ester exchange
method, raw material components are melted under high temperature
and subjected to an ester exchange reaction for polymerization. The
branched polycarbonate to be obtained is liable to color owing to,
for example, an influence by a polymerization catalyst to be used
in the reaction. Therefore, it is not preferred to produce the
branched polycarbonate through the use of the ester exchange method
in an application where transparency is required.
As a method of producing the branched polycarbonate through the use
of the interfacial polymerization method, in Patent Document 1,
there is a disclosure of two production methods, i.e., a method
involving using a polycarbonate oligomer into which a branching
agent has been incorporated, and causing the polycarbonate oligomer
and a dihydric phenol to react with each other to provide the
branched polycarbonate, and a method involving using a
polycarbonate oligomer into which no branching agent has been
incorporated, and causing the polycarbonate oligomer, and a
branching agent and a dihydric phenol to react with one another to
provide the branched polycarbonate.
In the former method involving using the polycarbonate oligomer
into which the branching agent has been incorporated, and causing
the polycarbonate oligomer and the dihydric phenol to react with
each other to provide the branched polycarbonate, a unit derived
from the branching agent in the branched polycarbonate becomes more
uniform as compared to the latter method involving using the
polycarbonate oligomer into which no branching agent has been
incorporated, and causing the polycarbonate oligomer, and the
branching agent and the dihydric phenol to react with one another
to provide the branched polycarbonate, and hence physical
properties become more uniform than those in the latter production
method. Accordingly, the former method is a preferred method.
However, the method involving using the polycarbonate oligomer,
into which the branching agent has been incorporated, and causing
the polycarbonate oligomer and the dihydric phenol to react with
each other to provide the branched polycarbonate involves the
following problem. When the polycarbonate oligomer into which the
branching agent has been incorporated is continuously produced, an
intermediate phase occurs at the time of the separation of a
reaction liquid containing the polycarbonate oligomer into which
the branching agent has been incorporated into an organic solvent
phase containing the polycarbonate oligomer and an aqueous phase to
deteriorate separability, and hence production efficiency
remarkably reduces.
CITATION LIST
Patent Document
Patent Document 1: JP 7-103235 B2
SUMMARY OF INVENTION
Technical Problem
An object of the present invention is to provide a method by which
a branched polycarbonate is produced with high production
efficiency at the time of the production of the branched
polycarbonate through the use of an interfacial polymerization
method, the production method including using a polycarbonate
oligomer into which a branching agent has been incorporated, and
causing the polycarbonate oligomer and a dihydric phenol to react
with each other.
Solution to Problem
The inventors of the present invention have made extensive
investigations, and as a result, have found that the object is
achieved by setting a relationship between the addition amount of a
polymerization catalyst to be added and the chloroformate group
amount of the polycarbonate oligomer to a specific ratio at the
time of the production of the polycarbonate oligomer. Thus, the
inventors have completed the present invention.
That is, the present invention relates to the following items [1]
to [11].
[1] A method of producing a branched polycarbonate, comprising:
a step (a) of subjecting an alkali aqueous solution of a dihydric
phenol, phosgene, and a branching agent to a phosgenation reaction
in the presence of an organic solvent to provide a reaction
liquid;
a step (b) of adding the alkali aqueous solution of the dihydric
phenol and a polymerization catalyst to the reaction liquid
obtained from the step (a) to provide a reaction liquid containing
a polycarbonate oligomer;
a step (c) of separating the reaction liquid containing the
polycarbonate oligomer obtained in the step (b) into an organic
solvent phase containing the polycarbonate oligomer and an aqueous
phase; and
a step (d) of causing the organic solvent phase containing the
polycarbonate oligomer separated in the step (c) and the alkali
aqueous solution of the dihydric phenol to react with each other to
provide a reaction liquid containing the branched
polycarbonate,
wherein a ratio (x/y) of an addition amount of the polymerization
catalyst to be added in the step (b), which is represented by x
mol/hr, to a chloroformate group amount of the polycarbonate
oligomer in the reaction liquid obtained from the step (b), which
is represented by y mol/hr, is 0.0035 or more.
[2] The method of producing a branched polycarbonate according to
Item [1], wherein the polycarbonate oligomer has a weight-average
molecular weight of 5,000 or less.
[3] The method of producing a branched polycarbonate according to
Item [1] or [2], wherein the branching agent comprises a compound
represented by the following general formula (I):
##STR00001##
wherein R represents a hydrogen atom or an alkyl group having 1 to
5 carbon atoms, and R.sup.1 to R.sup.6 each represent a hydrogen
atom, an alkyl group having 1 to 5 carbon atoms, or a halogen
atom.
[4] The method of producing a branched polycarbonate according to
Item [3], wherein the compound represented by the general formula
(I) comprises 1,1,1-tris(4-hydroxyphenyl)ethane.
[5] The method of producing a branched polycarbonate according to
any one of Items [1] to [4], wherein the dihydric phenol comprises
a compound represented by the following general formula (1):
##STR00002##
wherein R.sup.11 and R.sup.12 each independently represent a
halogen atom, an alkyl group having 1 to 6 carbon atoms, or an
alkoxy group having 1 to 6 carbon atoms, Z represents a single
bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene
group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to
15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon
atoms, a fluorenediyl group, an arylalkylene group having 7 to 15
carbon atoms, an arylalkylidene group having 7 to 15 carbon atoms,
--S--, --SO--, --SO.sub.2--, --O--, or --CO--, and a and b each
independently represent an integer of from 0 to 4.
[6] The method of producing a branched polycarbonate according to
Item [5], wherein the compound represented by the general formula
(1) comprises 2,2-bis(4-hydroxyphenyl)propane.
[7] The method of producing a branched polycarbonate according to
any one of Items [1] to [6], further comprising adding a terminal
stopper to the reaction liquid obtained from the step (a).
[8] The method of producing a branched polycarbonate according to
any one of Items [1] to [7], further comprising a step (e) of
separating the reaction liquid containing the branched
polycarbonate obtained in the step (d) into an organic solvent
phase containing the branched polycarbonate and an aqueous phase
containing an unreacted dihydric phenol.
[9] The method of producing a branched polycarbonate according to
Item [8], wherein at least part of the aqueous phase containing the
unreacted dihydric phenol separated in the step (e) is used as the
alkali aqueous solution of the dihydric phenol to be added in the
step (b).
[10] The method of producing a branched polycarbonate according to
any one of Items [1] to [9], wherein the chloroformate group amount
of the polycarbonate oligomer in the reaction liquid obtained from
the step (b) is defined as a molar amount per unit time of the
organic solvent phase containing the polycarbonate oligomer
separated in the step (c).
[11] The method of producing a branched polycarbonate according to
any one of Items [1] to [10], wherein the polymerization catalyst
comprises triethylamine.
Advantageous Effects of Invention
According to the method of producing a branched polycarbonate of
the present invention, the occurrence of an intermediate phase can
be suppressed at the time of the separation of the reaction liquid
containing the polycarbonate oligomer into the organic solvent
phase containing the polycarbonate oligomer and the aqueous phase,
and hence separability is improved and the production efficiency of
the branched polycarbonate can be improved.
BRIEF DESCRIPTION OF DRAWINGS
FIGURE is a schematic view of a product ion process for a branched
polycarbonate of the present invention.
DESCRIPTION OF EMBODIMENTS
A method of producing a branched polycarbonate of the present
invention comprises: a step (a) of subjecting an alkali aqueous
solution of a dihydric phenol, phosgene, and a branching agent to a
phosgenation reaction in the presence of an organic solvent to
provide a reaction liquid; a step (b) of adding the alkali aqueous
solution of the dihydric phenol and a polymerization catalyst to
the reaction liquid obtained from the step (a) to provide a
reaction liquid containing a polycarbonate oligomer; a step (c) of
separating the reaction liquid containing the polycarbonate
oligomer obtained in the step (b) into an organic solvent phase
containing the polycarbonate oligomer and an aqueous phase; and a
step (d) of causing the organic solvent phase containing the
polycarbonate oligomer separated in the step (c) and the alkali
aqueous solution of the dihydric phenol to react with each other to
provide a reaction liquid containing the branched polycarbonate,
wherein a ratio (x/y) of an addition amount of the polymerization
catalyst to be added in the step (b), which is represented by x
mol/hr, to a chloroformate group amount of the polycarbonate
oligomer in the reaction liquid obtained from the step (b), which
is represented by y mol/hr, is 0.0035 or more.
The method of producing a branched polycarbonate of the present
invention is described in detail below. In this description, a
provision considered to be preferred can be arbitrarily adopted,
and a combination of preferred provisions can be said to be more
preferred.
[Step (a)]
The step (a) is a step of subjecting the alkali aqueous solution of
the dihydric phenol, phosgene, and the branching agent to the
phosgenation reaction in the presence of the organic solvent to
provide the reaction liquid. Raw materials to be used in the step
(a) and reaction conditions for the step are described.
<Alkali Aqueous Solution of Dihydric Phenol>
A dihydric phenol to be used in the production of a polycarbonate
is used as the dihydric phenol. A dihydric phenol represented by
the following general formula (1) is preferably used as the
dihydric phenol:
##STR00003##
wherein
in the general formula (1), R.sup.11 and R.sup.12 each
independently represent a halogen atom, an alkyl group having 1 to
6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, Z
represents a single bond, an alkylene group having 1 to 8 carbon
atoms, an alkylidene group having 2 to 8 carbon atoms, a
cycloalkylene group having 5 to 15 carbon atoms, a cycloalkylidene
group having 5 to 15 carbon atoms, a fluorenediyl group, an
arylalkylene group having 7 to 15 carbon atoms, an arylalkylidene
group having 7 to 15 carbon atoms, --S--, --SO--, --SO.sub.2--,
--O--, or --CO--, and a and b each independently represent an
integer of from 0 to 4.
The dihydric phenol represented by the general formula (1) is not
particularly limited, but 2,2-bis(4-hydroxyphenyl)propane [trivial
name: bisphenol A] is suitable.
Examples of the dihydric phenol except bisphenol A include:
bis(hydroxyaryl)alkanes, such as bis(4-hydroxyphenyl)methane,
1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane,
2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane,
bis(4-hydroxyphenyl)diphenylmethane,
2,2-bis(4-hydroxy-3-methylphenyl)propane,
bis(4-hydroxyphenyl)naphthylmethane,
1,1-bis(4-hydroxy-t-butylphenyl)propane,
2,2-bis(4-hydroxy-3-bromophenyl)propane,
2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane,
2,2-bis(4-hydroxy-3-chlorophenyl)propane,
2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, and
2,2-bis(4-hydroxy-3,5-dibromophenyl)propane;
bis(hydroxyaryl)cycloalkanes, such as
1,1-bis(4-hydroxyphenyl)cyclopentane,
1,1-bis(4-hydroxyphenyl)cyclohexane,
1,1-bis(4-hydroxyphenyl)-3,5,5-trimethylcyclohexane,
2,2-bis(4-hydroxyphenyl)norbornane, and
1,1-bis(4-hydroxyphenyl)cyclododecane; dihydroxyaryl ethers, such
as 4,4'-dihydroxydiphenyl ether and
4,4'-dihydroxy-3,3'-dimethylphenyl ether; dihydroxydiaryl sulfides,
such as 4,4'-dihydroxydiphenyl sulfide and
4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; dihydroxydiaryl
sulfoxides, such as 4,4'-dihydroxydiphenyl sulfoxide and
4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; dihydroxydiaryl
sulfones, such as 4,4'-dihydroxydiphenyl sulfone and
4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone; dihydroxydiphenyls,
such as 4,4'-dihydroxydiphenyl; dihydroxydiarylfluorenes, such as
9,9-bis(4-hydroxyphenyl)fluorene and
9,9-bis(4-hydroxy-3-methylphenyl)fluorene;
dihydroxydiaryladamantanes, such as
1,3-bis(4-hydroxyphenyl)adamantane,
2,2-bis(4-hydroxyphenyl)adamantane, and
1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane;
4,4'-[1,3-phenylenebis(1-methylethylidene)]bisphenol;
10,10-bis(4-hydroxyphenyl)-9-anthrone; and
1,5-bis(4-hydroxyphenylthio)-2,3-dioxapentane.
Each of those dihydric phenols may be used alone, or two or more
thereof may be used as a mixture.
The dihydric phenol is used as an alkali aqueous solution, and an
alkali to be used at this time may be, for example, an alkali
hydroxide, in particular, a strongly basic hydroxide, such as
sodium hydroxide or potassium hydroxide. Normally, an alkali
aqueous solution having an alkali concentration of from 1 mass % to
15 mass % is preferably used as the alkali aqueous solution. In
addition, the content of the dihydric phenol in the alkali aqueous
solution is typically selected from the range of from 0.5 mass % to
20 mass %.
<Phosgene>
Phosgene to be used in the step (a) is a compound obtained by
causing chlorine and carbon monoxide to react with each other at a
ratio of carbon monoxide of typically from 1.01 mol to 1.3 mol with
respect to 1 mol of chlorine through the use of activated carbon as
a catalyst. When phosgene is used as a phosgene gas, a phosgene gas
containing about 1 vol % to about 30 vol % of unreacted carbon
monoxide can be used. Phosgene in a liquefied state can also be
used.
<Branching Agent>
The branching agent to be used in the step (a) is not particularly
limited, and a known branching agent can be used. A branched
polycarbonate that hardly causes drawdown at the time of its
melting can be obtained by using, among the known branching agents,
a compound represented by the following general formula (I):
##STR00004##
wherein R represents a hydrogen atom or an alkyl group having 1 to
5 carbon atoms, and R.sup.1 to R.sup.6 each represent a hydrogen
atom, an alkyl group having 1 to 5 carbon atoms, or a halogen
atom.
In the general formula (I), examples of the alkyl group having 1 to
5 carbon atoms represented by R include a methyl group, an ethyl
group, a n-propyl group, a n-butyl group, and a n-pentyl group. In
addition, examples of the alkyl group having 1 to 5 carbon atoms
represented by each of R.sup.1 to R.sup.6 include a methyl group,
an ethyl group, a n-propyl group, a n-butyl group, and a n-pentyl
group, and examples of the halogen atom represented by each of
R.sup.1 to R.sup.6 include a chlorine atom, a bromine atom, and a
fluorine atom. Specific examples of the branching agent represented
by the general formula (I) include
1,1,1-tris(4-hydroxyphenyl)methane,
1,1,1-tris(4-hydroxyphenyl)ethane,
1,1,1-tris(4-hydroxyphenyl)propane,
1,1,1-tris(2-methyl-4-hydroxyphenyl)methane,
1,1,1-tris(2-methyl-4-hydroxyphenyl)ethane,
1,1,1-tris(3-methyl-4-hydroxyphenyl)methane,
1,1,1-tris(3-methyl-4-hydroxyphenyl)-ethane,
1,1,1-tris(3,5-dimethyl-4-hydroxyphenyl)methane,
1,1,1-tris(3,5-dimethyl-4-hydroxyphenyl)ethane,
1,1,1-tris(3-chloro-4-hydroxyphenyl)methane,
1,1,1-tris(3-chloro-4-hydroxyphenyl)ethane,
1,1,1-tris(3,5-dichloro-4-hydroxyphenyl)methane,
1,1,1-tris(3,5-dichloro-4-hydroxyphenyl)ethane,
1,1,1-tris(3-bromo-4-hydroxyphenyl)methane,
1,1,1-tris(3-bromo-4-hydroxyphenyl)ethane,
1,1,1-tris(3,5-dibromo-4-hydroxyphenyl)methane, and
1,1,1-tris(3,5-dibromo-4-hydroxyphenyl)ethane. Among the branching
agents each represented by the general formula (I),
1,1,1-tris(4-hydroxyphenyl)ethane [hereinafter sometimes referred
to as THPE] is particularly preferably used from the viewpoint of
the branching property of the branched polycarbonate.
<Organic Solvent>
The organic solvent to be used in the step (a) is, for example, a
solvent that dissolves a polycarbonate oligomer and a branched
polycarbonate. Specific examples thereof include halogenated
hydrocarbon solvents, such as dichloromethane (methylenechloride),
dichloroethane, trichloroethane, tetrachloroethane,
pentachloroethane, hexachloroethane, dichloroethylene,
chlorobenzene, and dichlorobenzene. Among them, dichloromethane
(methylene chloride) is particularly preferred.
<Reactor>
In the step (a), the alkali aqueous solution of the dihydric phenol
and the branching agent, and phosgene intensely react with one
another to involve heat generation, and hence the reaction product
is desirably cooled to from 0.degree. C. to 50.degree. C. in order
to suppress a side reaction. Therefore, a reactor provided with a
cooling facility for cooling the reaction product is preferably
used as a reactor to be used in the step (a). In addition, when the
alkali aqueous solution of the dihydric phenol, phosgene, the
branching agent, and the organic solvent are continuously
introduced into the reactor, the raw materials are preferably
subjected to the phosgenation reaction in such a state that the
reaction liquid is brought into a turbulent state in the reactor. A
mixing reactor is desirably used as such reactor, and the mixing
reactor is preferably a static mixer. The static mixer is
preferably a tubular reactor having in itself an element having an
action of dividing, converting, or inverting a fluid, and the
element generally has a shape obtained by twisting a rectangular
plate by 180.degree.. The reaction mixture introduced into the
reactor is divided into two portions every time the mixture passes
one element. In addition, the reaction mixture fluid or the
reaction product fluid are converted by moving from the central
portion of the tube to the wall portion thereof and from the wall
portion of the tube to the central portion along a spiral surface
in the element. In addition, the rotation direction of the fluid is
changed every one element, and hence the fluid undergoes abrupt
inversion of an inertial force to be turbulently stirred.
When the tubular static mixer described above is used as the
reactor, in the reactor, air bubbles in the liquid are reduced in
size to enlarge a contact interface between the raw materials, and
hence reaction efficiency is drastically improved.
<Ratio at which Each Raw Material is Introduced into
Reactor>
The alkali aqueous solution of the dihydric phenol, phosgene, the
branching agent, and the organic solvent are introduced into the
reactor to be used in the step (a), and are mixed and subjected to
the phosgenation reaction. Here, the usage amount of the organic
solvent is desirably selected so that a volume ratio between an
organic solvent phase and an aqueous phase may be from 5/1 to 1/7,
preferably from 2/1 to 1/4. With regard to the usage amount of
phosgene, phosgene is preferably used in excess so that its amount
may be typically from 1.05 mol to 1.5 mol, preferably from 1.1 mol
to 1.3 mol with respect to 1 mol of the dihydric phenol. With
regard to a usage molar ratio between the dihydric phenol and the
branching agent, the dihydric phenol and the branching agent are
preferably used so that a molar ratio "dihydric phenol:branching
agent" may typically fall within the range of from 99:1 to 90:10,
and preferably fall within the range of from 98:2 to 92:8. The
branching agent is desirably introduced after having been dissolved
in the alkali aqueous solution because the branching agent
represented by the general formula (I) can be dissolved in the
alkali aqueous solution, though the solubility of the branching
agent varies depending on the branching agent to be used. A
branching agent that is difficult to dissolve in the alkali aqueous
solution is desirably introduced after having been dissolved in an
organic solvent, such as methylene chloride.
In the phosgenation reactor, heat is generated by a reaction in
which terminal groups of the dihydric phenol and the branching
agent are each turned into a chloroformate by phosgene, or a
reaction in which phosgene is decomposed by the alkali, and hence
the temperature of the reaction product increases. Accordingly, the
reaction product is preferably cooled so that the temperature may
be from 0.degree. C. to 80.degree. C., preferably from 5.degree. C.
to 70.degree. C. When the tubular static mixer described above is
used as the reactor, an exothermic reaction starts from the
confluence point of the alkali aqueous solution of the dihydric
phenol and the branching agent, and phosgene, and hence the cooling
is preferably performed also at the confluence point. As the
reaction product flows in the reactor of the tubular static mixer
toward the outlet of the reactor, phosgene is consumed and hence
the generation of intense heat of reaction is prevented. A primary
object of the reaction in the step (a) is to turn each of the
terminal groups of the dihydric phenol and the branching agent into
a chloroformate with phosgene, and hence substantially no
oligomerization reaction advances.
[Step (b)]
The step (b) is a step of adding the alkali aqueous solution of the
dihydric phenol and the polymerization catalyst to the reaction
liquid obtained from the step (a) to provide the reaction liquid
containing the polycarbonate oligomer. Raw materials to be used in
the step (b) and reaction conditions for the step are
described.
As described above, substantially no oligomerization reaction
advances in the step (a), and hence the polycarbonate oligomer is
produced by performing an oligomerization reaction in the step (b)
to increase the molecular weight of the reaction product of the
step (a). In the step (b), the oligomerization reaction is
performed by adding the alkali aqueous solution of the dihydric
phenol and the polymerization catalyst to the reaction liquid
obtained from the step (a). The alkali aqueous solution of the
dihydric phenol described in the step (a) is used as the alkali
aqueous solution of the dihydric phenol to be used here.
<Polymerization Catalyst>
A known catalyst to be used at the time of the interfacial
polymerization of a polycarbonate resin can be used as the
polymerization catalyst to be used in the step (b). A phase
transfer catalyst, such as a tertiary amine or a salt thereof, a
quaternary ammonium salt, or a quaternary phosphonium salt, can be
preferably used as the catalyst. Examples of the tertiary amine
include triethylamine, tributylamine, N,N-dimethylcyclohexylamine,
pyridine, and dimethylaniline, and examples of the tertiary amine
salt include hydrochloric acid salts and bromic acid salts of the
tertiary amines. Examples of the quaternary ammonium salt include
trimethylbenzylammonium chloride, triethylbenzylammonium chloride,
tributylbenzylammonium chloride, trioctylmethylammonium chloride,
tetrabutylammonium chloride, and tetrabutylammonium bromide, and
examples of the quaternary phosphonium salt include
tetrabutylphosphonium chloride and tetrabutylphosphonium bromide.
Each of those catalysts may be used alone, or two or more thereof
may be used in combination. Among the catalysts, tertiary amines
are preferred, and triethylamine is particularly suitable. When the
catalyst is in a liquid state, each of those catalysts can be
introduced as it is or after having been dissolved in an organic
solvent or water. When the catalyst is in a solid state, each of
those catalysts can be introduced after having been dissolved in an
organic solvent or water.
A stirring tank is generally used as a reactor to be used in the
step (b). The stirring tank is not particularly limited as long as
the stirring tank is a tank-type one having a stirrer.
The reaction liquid obtained from the step (a) is introduced into
the reactor for advancing the oligomerization reaction. The
residual amounts of an unreacted dihydric phenol and a remaining
alkali component in the reaction liquid obtained from the step (a)
are small, and hence in order that the oligomerization reaction may
be advanced, the reaction needs to be performed by adding the
dihydric phenol and the alkali component, furthermore.
The oligomerization reaction of the step (b) is advanced by a
reaction between a compound in which the terminal groups of the
dihydric phenol and the branching agent have each been turned into
a chloroformate by phosgene in the reaction liquid obtained from
the step (a), and the dihydric phenol in the presence of the alkali
in the reactor to be used. In the method of producing a branched
polycarbonate of the present invention, the oligomerization
reaction can be advanced by, for example, introducing the alkali
aqueous solution of the dihydric phenol prepared in advance to be
used in the step (a) into the reactor, and introducing the alkali
aqueous solution prepared in advance into the reactor in addition
to the foregoing solution.
As another method, the oligomerization reaction can be advanced by:
recycling an aqueous phase out of an organic solvent phase and the
aqueous phase obtained by the separation of the reaction liquid
containing the branched polycarbonate obtained after a
polycondensation step [aqueous phase obtained in a step (e) to be
described later]; and introducing the recycled aqueous phase into
the reactor of the step (b). The aqueous phase obtained in the step
(e) contains an unreacted dihydric phenol and an alkali, and the
dihydric phenol and the alkali can be effectively used by recycling
the aqueous phase. The aqueous phase after the polycondensation
step may contain sodium carbonate produced by a decomposition
reaction of a chloroformate group of the polycarbonate oligomer
without contributing to polymerization and sodium hydroxide during
polycondensation.
The dihydric phenol to be added in the step (b) is desirably added
at a concentration of typically from 0.05 mol/L to 0.15 mol/L
(here, L means liter), preferably from 0.06 mol/L to 0.12 mol/L,
more preferably from 0.06 mol/L to 0.08 mol/L, and the alkali to be
added in the step (b) is desirably added at a concentration of
typically from 0.03 mol/L to 0.25 mol/L, preferably from 0.05 mol/L
to 0.22 mol/L, more preferably from 0.10 mol/L to 0.22 mol/L. The
usage amount of the organic solvent in the reaction liquid of the
step (b) is typically selected so that a volume ratio between an
organic phase and an aqueous phase may be preferably from 5/1 to
1/7, more preferably from 2/1 to 1/4.
The step (b) is a step of obtaining the reaction liquid containing
the polycarbonate oligomer, and an upper limit for the
weight-average molecular weight of the oligomer is preferably
5,000, and a lower limit therefor is typically about 500. In the
step (b), a terminal stopper is preferably added for setting the
weight-average molecular weight of the polycarbonate oligomer to
5,000 or less. The addition of the terminal stopper facilitates the
adjustment of the weight-average molecular weight of the
polycarbonate oligomer in the step (b) to 5,000 or less. The
terminal stopper is not particularly limited, and a terminal
stopper to be used in the production of a polycarbonate can be
used. Specific examples of a compound to be used as the terminal
stopper may include monohydric phenols, such as phenol, p-cresol,
p-tert-butylphenol, p-tert-octylphenol, p-cumylphenol,
3-pentadecylphenol, bromophenol, tribromophenol, and nonylphenol.
Among them, at least one selected from p-tert-butylphenol,
p-cumylphenol, and phenol is preferred in terms of, for example,
economical efficiency and ease of availability. Each of those
terminal stoppers may be introduced into the step (b) after having
been dissolved in an organic solvent, such as methylene chloride,
and having been added to the reaction liquid obtained from the step
(a), or may be introduced by direct addition to the reactor to be
used in the step (b).
The reaction is performed while a temperature in the reactor in the
step (b) is maintained at a temperature within the range of
typically from 5.degree. C. to 50.degree. C., preferably from
5.degree. C. to 40.degree. C. With regard to a stirring condition,
the reaction liquid is stirred under such a relatively moderate
condition that the liquid becomes a laminar flow. The retention
time of the reaction liquid in the reactor is generally from 15
minutes to 60 minutes, though the time varies depending on, for
example, the target molecular weight of the polycarbonate oligomer
and the properties of the reaction liquid obtained from the step
(a).
In the method of producing a branched polycarbonate of the present
invention, a ratio (x/y) of the addition amount of the
polymerization catalyst to be added in the step (b), which is
represented by x mol/hr, to the chloroformate group amount of the
polycarbonate oligomer in the reaction liquid obtained from the
step (b), which is represented by y mol/hr, needs to be 0.0035 or
more. A ratio (x/y) of less than 0.0035 is not preferred because
when the reaction liquid obtained from the step (b) is separated
into the organic solvent phase containing the polycarbonate
oligomer and the aqueous phase in the step (c), a large amount of
an intermediate phase occurs to deteriorate the separability of the
reaction liquid, and hence the production efficiency of the
branched polycarbonate reduces. The ratio (x/y) is preferably
0.0038 or more, more preferably 0.0042 or more. An upper limit for
the ratio (x/y) is typically 0.023 or less from the viewpoint that
a reducing effect on the production amount of the intermediate
phase does not change. In order to set the ratio (x/y) to the
above-mentioned value, in normal cases, the addition amount of the
polymerization catalyst to be added in the step (b) is desirably
adjusted in accordance with the chloroformate group amount of the
polycarbonate oligomer in the reaction liquid obtained from the
step (b).
The chloroformate group amount of the polycarbonate oligomer in the
reaction liquid obtained from the step (b) is measured as described
below. The reaction liquid containing the polycarbonate oligomer
obtained from the step (b) is sampled, and is separated into the
organic solvent phase containing the polycarbonate oligomer and the
aqueous phase by, for example, settled separation or centrifugal
separation. The chloroformate group concentration of the
polycarbonate oligomer in the resultant organic solvent phase is
determined, and a molar amount per unit time can be determined from
the chloroformate group concentration and the amount (flow rate) of
the organic solvent phase containing the polycarbonate oligomer
separated from the reaction liquid obtained from the step (b).
Alternatively, the molar amount per unit time can also be
determined as follows: the reaction liquid obtained from the step
(b) is separated in the step (c), and the molar amount per unit
time is determined from the extraction amount (flow rate) of the
separated organic solvent phase containing the polycarbonate
oligomer and the chloroformate group concentration of the
oligomer.
[Step (c)]
The step (c) is a step of separating the reaction liquid containing
the polycarbonate oligomer obtained in the step (b) into the
organic solvent phase containing the polycarbonate oligomer and the
aqueous phase. A settled separation tank is preferably used as an
apparatus to be used in the step (c). The reaction liquid
containing the polycarbonate oligomer obtained in the step (b) is
introduced into the settled separation tank, and is separated into
the organic solvent phase containing the polycarbonate oligomer and
the aqueous phase by their specific gravity difference. The organic
solvent phase containing the polycarbonate oligomer serving as a
lower layer is continuously or intermittently extracted from the
lower side of the settled separation tank. The aqueous phase
serving as an upper layer is continuously or intermittently
extracted, and the level of each phase in the settled separation
tank is maintained so as to fall within a certain level range. In
the step (c), the organic solvent phase containing the
polycarbonate oligomer is continuously or intermittently extracted
from the lower side of the settled separation tank. Here, as
described above, a value for the ratio (x/y) can be determined from
the chloroformate group concentration of the polycarbonate oligomer
in the organic solvent phase determined in advance and the
extraction amount of the phase.
[Step (d)]
The step (d) is a step of causing the organic solvent phase
containing the polycarbonate oligomer separated in the step (c) and
the alkali aqueous solution of the dihydric phenol to react with
each other to provide the reaction liquid containing the branched
polycarbonate. In the step (d), the polycarbonate oligomer and the
dihydric phenol are subjected to a polycondensation reaction in the
presence of the alkali aqueous solution and the organic solvent,
and the molecular weight of the branched polycarbonate is adjusted
to fall within a target molecular weight range. The
polycondensation reaction is performed until the molecular weight
of the branched polycarbonate to be obtained typically falls within
the range of from about 10,000 to about 50,000 in terms of a
viscosity-average molecular weight.
Specifically, the organic solvent phase containing the
polycarbonate oligomer separated in the step (c), the terminal
stopper to be used as desired, the catalyst to be used as desired,
the organic solvent, the alkali aqueous solution, and the alkali
aqueous solution of the dihydric phenol are mixed, and the mixture
is subjected to interfacial polycondensation at a temperature in
the range of typically from 0.degree. C. to 50.degree. C.,
preferably from 20.degree. C. to 40.degree. C.
Examples of the alkali of the alkali aqueous solution, the organic
solvent, the terminal stopper, and the catalyst to be used in the
step (d) may include the same examples as those described in the
step (a) or (b). In the step (d), the usage amount of the organic
solvent in the interfacial polycondensation is typically selected
so that a volume ratio between an organic phase and an aqueous
phase may be preferably from 7/1 to 1/1, more preferably from 5/1
to 2/1.
With regard to a reactor to be used in the step (d), the reaction
can be completed with only one reactor depending on the ability of
the reactor. A plurality of reactors, such as a second reactor and
a third reactor subsequent to the first reactor, can also be
further constructed and used as required. A stirring tank, a
tower-type stirring tank with a vertical multistage impeller, a
non-stirring tank, a static mixer, a line mixer, an orifice mixer,
a pipe, and the like can be used as those reactors. Those reactors
may be arbitrarily combined to be used as a plurality of
reactors.
As described above, the reaction liquid containing the branched
polycarbonate is obtained by the step (a) to the step (d). It is
preferred that the method of producing a branched polycarbonate of
the present invention further include the following step (e), and
at least part of an aqueous phase containing an unreacted dihydric
phenol from the following step (e) be used as the alkali aqueous
solution of the dihydric phenol to be added in the step (b). The
step (e) is described below.
[Step (e)]
The step (e) is a step of separating the reaction liquid containing
the branched polycarbonate obtained in the step (d) into an organic
solvent phase containing the branched polycarbonate and the aqueous
phase containing the unreacted dihydric phenol. An apparatus to be
used for the separation into the organic solvent phase containing
the branched polycarbonate and the aqueous phase containing the
unreacted dihydric phenol in the step (e) may be, for example, a
settling tank or a centrifugal separator. The organic solvent phase
containing the branched polycarbonate separated in the step (e) is
sequentially subjected to alkali washing, acid washing, and pure
water washing to provide an organic solvent phase containing a
purified branched polycarbonate. The organic solvent phase
containing the purified polycarbonate is concentrated as required
to provide an organic solvent solution containing the purified
polycarbonate, and the solution is subjected to a kneader
treatment, warm water granulation, or the like. Thus, branched
polycarbonate powder can be obtained. The organic solvent remains
in the resultant branched polycarbonate powder, and hence branched
polycarbonate powder from which the organic solvent has been
removed can be obtained by performing a drying treatment, such as a
heating treatment. Various molded bodies can be obtained by
pelletizing the resultant branched polycarbonate powder with a
pelletizer or the like.
The aqueous phase separated in the step (e) contains the unreacted
dihydric phenol and the alkali, and the total amount or part of the
aqueous phase is preferably recycled in the step (b) from the
viewpoint of effective utilization of the raw materials.
EXAMPLES
The present invention is hereinafter described more specifically by
way of Examples. The present invention is not limited by these
examples. Measurements and evaluations in Examples and Comparative
Examples were performed by the following methods.
<Measurement of Weight-average Molecular Weight (Mw)>
A weight-average molecular weight (Mw) was measured as a molecular
weight in terms of standard polystyrene (weight-average molecular
weight: Mw) by GPC [column: TOSOH TSK-GEL MULTIPORE HXL-M (2
columns)+Shodex KF801 (1 column), temperature: 40.degree. C., flow
rate: 1.0 ml/min, detector: RI] using tetrahydrofuran (THF) as a
developing solvent.
<Measurement of Chloroformate Group Concentration (CF
Value)>
Measurement was performed on the basis of a chlorine ion
concentration with reference to JIS K 8203 by using redox titration
and silver nitrate titration.
<Evaluation of Oligomerization Reaction Liquid in Settling
Tank>
With regard to the separability of an oligomerization reaction
liquid in a settling tank, the concentration of moisture in an
organic solvent phase and the thickness of an intermediate phase
after the liquid had been left at rest for 60 minutes were
measured. A larger numerical value for each of the concentration
and the thickness means that the separability is worse. A solid
matter content in an aqueous phase was determined by: loading
methylene chloride into the aqueous phase; mixing the aqueous phase
and methylene chloride; then subjecting the mixture to oil-water
separation to provide a methylene chloride phase; evaporating the
methylene chloride phase to dryness; measuring the weight of the
residue; and converting the weight into a mass fraction in the
solution. A larger solid matter content means that the intermediate
phase flows out toward the aqueous phase to a larger extent.
<Measurement of Viscosity-average Molecular Weight (Mv)>
The viscosity-average molecular weight (Mv) of a polycarbonate is
calculated from the following expression by using a limiting
viscosity [.eta.] determined by measuring the viscosity of a
methylene chloride solution at 20.degree. C. with an Ubbelohde-type
viscometer. [.eta.]=1.23.times.10.sup.-5 Mv.sup.0.83
Example 1
<Production of Polycarbonate Oligomer>
A polycarbonate oligomer was produced in accordance with a scheme
illustrated in FIGURE.
First, 6.0 mass % aqueous sodium hydroxide was prepared. Then, a
13.5 mass % (in terms of solid matter) solution of bisphenol A
(abbreviated as "BPA") in aqueous sodium hydroxide was prepared by
dissolving BPA in the aqueous sodium hydroxide. Next, a 24 mass %
solution was prepared by dissolving p-tert-butylphenol (PTBP) in
methylene chloride.
The solution of BPA in aqueous sodium hydroxide, methylene
chloride, and an 11 mass % (in terms of solid matter) solution of
1,1,1-tris(4-hydroxyphenyl)ethane (abbreviated as "THPE") in
aqueous sodium hydroxide prepared by dissolving THPE serving as a
branching agent in 5.1 mass % aqueous sodium hydroxide were
continuously supplied to a tubular reactor having an inner diameter
of 6 mm and a length of 26 m at flow rates of 36 L/hr, 15.4 L/hr,
and 0.7 L/hr, respectively. A molar ratio "dihydric phenol
(BPA):branching agent (THPE)" is 98.9:1.1. Simultaneously with the
supply, phosgene was continuously blown into the tubular reactor at
a flow rate of 3.1 kg/hr to perform a phosgenation reaction, and
the solution of PTBP was supplied at a flow rate of 310 mL/hr.
Thus, a reaction liquid containing a phosgenation reaction product
was obtained. At this time, the tubular reactor was cooled so that
the temperature of the reaction product at the outlet of the
tubular reactor became 30.degree. C. Phosgene used here was
separately synthesized from carbon monoxide (CO) and chlorine
(Cl.sub.2).
Then, an oligomerization reaction was performed by: continuously
supplying the reaction liquid and 210 mL/hr (0.062 mol/hr) of a 3
mass % aqueous solution of triethylamine (abbreviated as "TEA")
prepared in advance as a catalyst to an oligomerization reactor
[step (b)] having an internal volume of 100 L and provided with a
stirrer; and introducing 15.7 L/hr of a recycled aqueous phase
obtained from the step [step (e)] of separating a reaction liquid
obtained from a polycondensation reaction [step (d)] to be
described later into an aqueous phase and an organic solvent phase
containing a polycarbonate to the oligomerization reactor. The
concentration of BPA in an aqueous phase, "aqueous phase after the
confluence of the recycled aqueous phase from the [step (e)] and an
aqueous phase (pure water) to be additionally introduced for
concentration adjustment" before the introduction into the
oligomerization reactor, was 0.07 mol/L, the concentration of
sodium hydroxide therein was 0.13 mol/L, and the concentration of
sodium carbonate therein was 0.08 mol/L. The oligomerization
reaction was performed in a laminar flow state by rotating the
inside of the oligomerization reactor at 350 rpm. A reaction liquid
extracted from the bottom portion of the oligomerization reactor
was continuously supplied to a horizontal settling tank (having an
inner diameter of 350 mm and an internal volume of 100 L) through a
transfer pipe [made of SUS, pipe diameter: 12.7 mm (1/2 inch)], and
the separation of an aqueous phase and an organic solvent phase
[step (c)] was performed. The reaction liquid containing a
polycarbonate oligomer was separated into an aqueous phase and an
organic solvent phase in the horizontal settling tank. The organic
solvent phase was continuously extracted from the horizontal
settling tank at a flow rate of 20 L/hr, and a chloroformate group
concentration in the extracted organic solvent phase was 0.72
mol/L. In addition, the weight-average molecular weight of the
polycarbonate oligomer in the organic solvent phase was 3,100.
After the above-mentioned continuous operation had been performed
for 24 hours, the aqueous phase and the organic solvent phase in
the horizontal settling tank were observed. As a result, an
intermediate phase slightly occurred between the aqueous phase and
the organic solvent phase. However, the thickness of the
intermediate phase was about 9.0 mm (corresponding to 3.2 L), and
even when settled separation was continuously performed, the
thickness of the intermediate phase did not increase, and hence the
reaction liquid was able to be satisfactorily separated into the
aqueous phase and the organic solvent phase. A moisture content in
the organic solvent phase after the separation was 2,000 ppm by
mass, and a solid matter content in the aqueous phase after the
separation was less than 10 ppm by mass. The chloroformate group
amount (y) of the polycarbonate oligomer in the organic solvent
phase continuously extracted from the horizontal settling tank is
20.times.0.72=14 0.4 mol/hr. The addition amount (x) of TEA used as
a polymerization catalyst to the oligomerization reactor was 0.062
mol/hr, and hence a ratio (x/y) was equal to 0.0043.
<Production of Branched Polycarbonate>
A polycondensation reaction was performed in the step (d) by using
the organic solvent phase containing the polycarbonate oligomer
(sometimes abbreviated as "PCO") separated from the horizontal
settling tank in accordance with the scheme illustrated in FIGURE.
The organic solvent phase containing the polycarbonate oligomer
(PCO), the solution of BPA in aqueous sodium hydroxide (solution
used in the production of the polycarbonate oligomer), the aqueous
solution of TEA having a concentration of 3 mass % serving as a
catalyst, the solution of PTBP serving as a terminal stopper,
aqueous sodium hydroxide having a concentration of 20 mass %, and
methylene chloride serving as a solvent were introduced into the
polycondensation reactor of the step (d) at flow rates of 20 L/hr,
9.8 L/hr, 0.10 L/hr, 0.34 L/hr, 1.3 L/hr, and 13.5 L/hr,
respectively to perform the polycondensation reaction. Two
reactors, i.e., a line mixer and a tower-type reactor were used as
reactors used in the polycondensation reactor. A reaction mixture
overflowing out of the upper portion of the tower-type reactor was
subjected to settled separation to be separated into an aqueous
phase and an organic solvent phase [step (e)]. The total amount of
the separated aqueous phase was introduced into the oligomerization
reactor of the step (b) and recycled. In addition, the resultant
organic solvent phase was sequentially washed with aqueous sodium
hydroxide whose pH had been adjusted to 13.5, an aqueous solution
of hydrochloric acid whose pH had been adjusted to 1.5, and pure
water to provide a clear methylene chloride solution of a branched
polycarbonate.
Methylene chloride was removed from the resultant methylene
chloride solution of the branched polycarbonate by evaporation with
a kneader. Thus, branched polycarbonate powder was obtained.
Further, remaining methylene chloride was removed by heat drying
until its content became 100 ppm or less. Thus, white branched
polycarbonate powder was obtained. The viscosity-average molecular
weight (Mv) of the powder was measured. As a result, the
viscosity-average molecular weight was 23,000.
Example 2
The same procedure as that of Example 1 was performed except that
the flow rate of the 3 mass % aqueous solution of TEA added to the
oligomerization reactor [step (b)] was changed to 310 mL/hr (0.092
mol/hr), and the ratio (x/y) was set to 0.0064. At that time, an
intermediate phase slightly occurred between the aqueous phase and
the organic solvent phase. However, the thickness of the
intermediate phase was about 4 mm (corresponding to 1.4 L), and
even when settled separation was continuously performed, the
thickness of the intermediate phase did not increase, and hence the
reaction liquid was able to be satisfactorily separated into the
aqueous phase and the organic solvent phase. The viscosity-average
molecular weight (Mv) of the branched polycarbonate was measured.
As a result, the viscosity-average molecular weight was 23,000. The
weight-average molecular weight of the polycarbonate oligomer in
the organic solvent phase was 3,100, a moisture content in the
organic solvent phase after the separation was 2,000 ppm by mass,
and a solid matter content in the aqueous phase after the
separation was less than 10 ppm by mass.
Comparative Example 1
The same procedure as that of Example 1 was performed except that
the flow rate of the 3 mass % aqueous solution of TEA added to the
oligomerization reactor [step (b)] was changed to 110 mL/hr (0.033
mol/hr), and the ratio (x/y) was set to 0.0023. At that time, a
large amount of an intermediate phase occurred between the aqueous
phase and the organic solvent phase, and the thickness of the
intermediate phase reached about 42 mm (corresponding to 14.8 L).
The intermediated phase occurred in a large amount as described
above, and hence it became impossible to continuously perform
settled separation and it became difficult to continuously produce
a branched polycarbonate. The weight-average molecular weight of
the polycarbonate oligomer in the organic solvent phase was 3,100,
a moisture content in the organic solvent phase after the
separation was 2,000 ppm by mass, and a solid matter content in the
aqueous phase after the separation was less than 10 ppm by
mass.
Reference Example 1
In Example 1, a phosgenation reaction was performed without the
supply of the solution of THPE in aqueous sodium hydroxide at the
time of the phosgenation reaction. The flow rate of the 3 mass %
aqueous solution of TEA added to the oligomerization reactor [step
(b)] together with the resultant reaction liquid containing a
phosgenation reaction product was changed to 110 mL/hr (0.033
mol/hr), and the ratio (x/y) was set to 0.0023. The same procedure
as that of Example 1 was performed except the foregoing. At that
time, an intermediate phase slightly occurred between the aqueous
phase and the organic solvent phase. However, the thickness of the
intermediate phase was about 4 mm (corresponding to 1.4 L), and
even when settled separation was continuously performed, the
thickness of the intermediate phase did not increase, and hence the
reaction liquid was able to be satisfactorily separated into the
aqueous phase and the organic solvent phase. The viscosity-average
molecular weight (Mv) of the resultant unbranched polycarbonate was
measured. As a result, the viscosity-average molecular weight was
23,000.
It has been shown from Examples 1 and 2, and Comparative Example 1
of the present invention that in each of Examples 1 and 2 in which
in the step of obtaining the reaction liquid containing the
polycarbonate oligomer at the time of the production of the
branched polycarbonate, the ratio between the amount of the
polymerization catalyst to be added and the chloroformate group
amount of the polycarbonate oligomer in the reaction liquid to be
extracted is 0.0035 or more, the occurrence of an intermediate
phase is suppressed and hence settled separation can be
continuously performed. Meanwhile, it has been shown that in
Comparative Example 1 in which the ratio is less than 0.0035, a
large amount of an intermediate phase occurs to make it impossible
to continuously perform settled separation. It has been shown that
in Reference Example 1 in which no branching agent is used,
although the amount of the polymerization catalyst is the same as
that in Comparative Example 1, as in Examples 1 and 2, the
occurrence of an intermediate phase is suppressed and hence settled
separation can be continuously performed.
INDUSTRIAL APPLICABILITY
In the method of producing a branched polycarbonate of the present
invention, the separability of the reaction liquid containing the
polycarbonate oligomer is satisfactory in the step of separating
the reaction liquid, and hence the production efficiency of the
branched polycarbonate can be improved.
* * * * *